<?php

declare(strict_types=1);

namespace Sarcio\WordPress\Assistant;

use Sarcio\WordPress\KeptFixes;
use Sarcio\WordPress\Options;

/**
 * "This month on your site": what the assistant changed, who applied it and
 * whether it stayed, and the fixes kept on the site, for one calendar month
 * in the site's time zone. Shown under Sarcio → Report, printable, and mailed
 * on the first of the month to the addresses in the settings.
 */
final class Report
{
    public const CRON_HOOK = 'sarcio_monthly_report';
    public const SENT_OPTION = 'sarcio_report_sent';

    /** @return array{month:string,label:string,from:string,to:string,changes:array<int,array<string,mixed>>,kept:array<int,array<string,mixed>>,counts:array<string,int>} */
    public static function build(string $month, bool $everyChange = false): array
    {
        [$from, $to, $label] = self::bounds($month);
        $changes = [];
        foreach (Journal::between($from, $to) as $entry) {
            if ($entry['ability'] === 'sarcio/changes-undo' || (!$everyChange && !JournalAbilities::visible($entry))) {
                continue;
            }
            $changes[] = [
                'at' => $entry['createdAt'],
                'by' => self::userName($entry['userId']),
                'id' => $entry['id'],
                'label' => Catalog::label($entry['ability']),
                'summary' => $entry['summary'],
                'undoneAt' => $entry['undoneAt'],
            ];
        }
        $kept = [];
        $fromTs = (int) strtotime($from . ' UTC');
        $toTs = (int) strtotime($to . ' UTC');
        foreach (KeptFixes::all() as $id => $fix) {
            $keptAt = (int) ($fix['keptAt'] ?? 0);
            if ($keptAt >= $fromTs && $keptAt < $toTs) {
                $kept[] = [
                    'at' => gmdate('Y-m-d H:i:s', $keptAt),
                    'enabled' => !isset($fix['enabled']) || (bool) $fix['enabled'],
                    'id' => (string) $id,
                    'title' => (string) ($fix['title'] ?? $fix['summary'] ?? $id),
                ];
            }
        }
        $published = get_posts(['date_query' => [['after' => $from, 'before' => $to, 'column' => 'post_date_gmt']], 'numberposts' => 500, 'post_status' => 'publish', 'post_type' => ['page', 'post', 'product']]);
        $moderated = 0;
        $updated = 0;
        foreach ($changes as $change) {
            if ($change['label'] === Catalog::label('sarcio/comments-moderate')) {
                $moderated++;
            }
            if (in_array($change['label'], [Catalog::label('sarcio/plugin-update'), Catalog::label('sarcio/theme-update')], true)) {
                $updated++;
            }
        }
        $health = HealthAbilities::summary();
        $log = ActivityAbilities::counts($from, $to);
        return [
            'activity' => ['commentsModerated' => $moderated, 'log' => $log, 'published' => is_array($published) ? count($published) : 0, 'updates' => $updated],
            'changes' => $changes,
            'counts' => [
                'changes' => count($changes),
                'kept' => count($kept),
                'undone' => count(array_filter($changes, static fn (array $change): bool => $change['undoneAt'] !== null)),
            ],
            'health' => $health,
            'from' => $from,
            'kept' => $kept,
            'label' => $label,
            'month' => $month,
            'to' => $to,
        ];
    }

    /** The month that just ended, in the site's time zone, as YYYY-MM. */
    public static function previousMonth(): string
    {
        $now = new \DateTimeImmutable('now', self::timezone());
        return $now->modify('first day of last month')->format('Y-m');
    }

    public static function currentMonth(): string
    {
        return (new \DateTimeImmutable('now', self::timezone()))->format('Y-m');
    }

    /** The months a report can be shown for, newest first. */
    public static function months(int $count = 12): array
    {
        $out = [];
        $cursor = new \DateTimeImmutable('first day of this month', self::timezone());
        for ($i = 0; $i < $count; $i++) {
            $out[] = ['label' => self::label($cursor), 'month' => $cursor->format('Y-m')];
            $cursor = $cursor->modify('first day of last month');
        }
        return $out;
    }

    /** The report as an email body: plain HTML a mail client renders the same everywhere. */
    public static function html(array $report, string $siteName): string
    {
        $esc = static fn (string $text): string => esc_html($text);
        $rows = '';
        foreach ($report['changes'] as $change) {
            $rows .= '<tr><td style="padding:6px 10px;border-bottom:1px solid #eee;white-space:nowrap">' . $esc(substr((string) $change['at'], 0, 10)) . '</td>'
                . '<td style="padding:6px 10px;border-bottom:1px solid #eee">' . $esc((string) $change['summary']) . '</td>'
                . '<td style="padding:6px 10px;border-bottom:1px solid #eee">' . $esc((string) $change['by']) . '</td>'
                . '<td style="padding:6px 10px;border-bottom:1px solid #eee">' . $esc($change['undoneAt'] !== null ? __('Undone', 'sarcio') : __('Applied', 'sarcio')) . '</td></tr>';
        }
        $keptRows = '';
        foreach ($report['kept'] as $fix) {
            $keptRows .= '<tr><td style="padding:6px 10px;border-bottom:1px solid #eee;white-space:nowrap">' . $esc(substr((string) $fix['at'], 0, 10)) . '</td>'
                . '<td style="padding:6px 10px;border-bottom:1px solid #eee">' . $esc((string) $fix['title']) . '</td>'
                . '<td style="padding:6px 10px;border-bottom:1px solid #eee">' . $esc($fix['enabled'] ? __('On', 'sarcio') : __('Off', 'sarcio')) . '</td></tr>';
        }
        $head = '<h1 style="font:600 22px -apple-system,Segoe UI,sans-serif;margin:0 0 4px">' . $esc(sprintf(
            /* translators: 1: the site name, 2: the month. */
            __('%1$s in %2$s', 'sarcio'),
            $siteName,
            $report['label'],
        )) . '</h1>';
        $summary = '<p style="font:15px -apple-system,Segoe UI,sans-serif;color:#444;margin:0 0 18px">' . $esc(sprintf(
            /* translators: 1: changes made, 2: changes undone, 3: fixes kept. */
            __('%1$d changes made through the assistant, %2$d of them undone. %3$d fixes kept on the site.', 'sarcio'),
            $report['counts']['changes'],
            $report['counts']['undone'],
            $report['counts']['kept'],
        )) . '</p>';
        $table = static fn (string $title, string $body, string $empty): string => '<h2 style="font:600 16px -apple-system,Segoe UI,sans-serif;margin:18px 0 6px">' . $esc($title) . '</h2>'
            . ($body !== '' ? '<table style="border-collapse:collapse;width:100%;font:14px -apple-system,Segoe UI,sans-serif">' . $body . '</table>' : '<p style="font:14px -apple-system,Segoe UI,sans-serif;color:#666">' . $esc($empty) . '</p>');
        $logo = \Sarcio\WordPress\Brand::logo();
        $footer = '<p style="font:12px -apple-system,Segoe UI,sans-serif;color:#888;margin:18px 0 0">' . $esc(sprintf(
            /* translators: %s: the brand name. */
            __('Sent by %s.', 'sarcio'),
            \Sarcio\WordPress\Brand::name(),
        )) . '</p>';
        $activity = $report['activity'] ?? ['commentsModerated' => 0, 'published' => 0, 'updates' => 0];
        $activityRow = '<tr><td style="padding:6px 10px;border-bottom:1px solid #eee">' . $esc(sprintf(
            /* translators: 1: pages published, 2: comments moderated, 3: updates. */
            __('%1$d pages, posts or products published · %2$d comments moderated · %3$d plugin or theme updates', 'sarcio'),
            (int) $activity['published'],
            (int) $activity['commentsModerated'],
            (int) $activity['updates'],
        )) . '</td></tr>';
        $log = is_array($activity['log'] ?? null) ? $activity['log'] : ['byType' => [], 'source' => 'wordpress'];
        if ($log['source'] !== 'wordpress' && $log['byType'] !== []) {
            $activityRow .= '<tr><td style="padding:6px 10px;border-bottom:1px solid #eee;color:#50575e">' . $esc(sprintf(
                /* translators: 1: the log plugin, 2: counts by type. */
                __('From %1$s: %2$s', 'sarcio'),
                $log['source'] === 'simple-history' ? 'Simple History' : 'Stream',
                implode(', ', array_map(static fn (string $type, int $count): string => $type . ' ' . $count, array_keys($log['byType']), $log['byType'])),
            )) . '</td></tr>';
        }
        $health = $report['health'] ?? ['counts' => ['critical' => 0, 'good' => 0, 'recommended' => 0], 'issues' => []];
        $healthRows = '<tr><td style="padding:6px 10px;border-bottom:1px solid #eee">' . $esc(sprintf(
            /* translators: 1: passed, 2: recommended, 3: critical. */
            __('Site Health: %1$d checks passed, %2$d recommended, %3$d critical', 'sarcio'),
            (int) $health['counts']['good'],
            (int) $health['counts']['recommended'],
            (int) $health['counts']['critical'],
        )) . '</td></tr>';
        foreach (array_slice((array) $health['issues'], 0, 8) as $issue) {
            $healthRows .= '<tr><td style="padding:6px 10px;border-bottom:1px solid #eee;color:' . ($issue['status'] === 'critical' ? '#b32d2e' : '#50575e') . '">' . $esc((string) $issue['label']) . '</td></tr>';
        }
        return '<div style="max-width:720px">' . ($logo !== '' ? '<img src="' . esc_url($logo) . '" alt="" style="max-height:40px;margin:0 0 12px" />' : '') . $head . $summary
            . $table(__('Changes', 'sarcio'), $rows, __('No changes this month.', 'sarcio'))
            . $table(__('Fixes kept on the site', 'sarcio'), $keptRows, __('No fixes were kept this month.', 'sarcio'))
            . $table(__('On the site', 'sarcio'), $activityRow, '')
            . $table(__('Health today', 'sarcio'), $healthRows, '')
            . $footer
            . '</div>';
    }

    /** Called daily by WP-Cron: on the first of the month, mails last month's report once. */
    public static function sendIfDue(?\DateTimeImmutable $now = null): bool
    {
        $recipients = self::recipients();
        if ($recipients === []) {
            return false;
        }
        $now = ($now ?? new \DateTimeImmutable('now'))->setTimezone(self::timezone());
        $month = $now->modify('first day of last month')->format('Y-m');
        if ((string) get_option(self::SENT_OPTION, '') === $month || (int) $now->format('j') !== 1) {
            return false;
        }
        return self::send($month, $recipients);
    }

    /** @param array<int,string> $recipients */
    public static function send(string $month, array $recipients): bool
    {
        $report = self::build($month, true);
        $siteName = html_entity_decode((string) get_bloginfo('name'), ENT_QUOTES | ENT_HTML5, 'UTF-8');
        $sent = wp_mail(
            $recipients,
            sprintf(
                /* translators: 1: the site name, 2: the month. */
                __('%1$s in %2$s: what changed', 'sarcio'),
                $siteName,
                $report['label'],
            ),
            self::html($report, $siteName),
            ['Content-Type: text/html; charset=UTF-8'],
        );
        if ($sent) {
            update_option(self::SENT_OPTION, $month, false);
        }
        return (bool) $sent;
    }

    /** @return array<int,string> */
    public static function recipients(): array
    {
        $raw = (string) Options::get('report_email');
        return array_values(array_filter(array_map('trim', explode(',', $raw)), static fn (string $email): bool => $email !== '' && is_email($email) !== false));
    }

    public static function schedule(): void
    {
        if (!wp_next_scheduled(self::CRON_HOOK)) {
            wp_schedule_event(time() + 3600, 'daily', self::CRON_HOOK);
        }
    }

    public static function unschedule(): void
    {
        $next = wp_next_scheduled(self::CRON_HOOK);
        if ($next) {
            wp_unschedule_event((int) $next, self::CRON_HOOK);
        }
    }

    /** @return array{0:string,1:string,2:string} UTC bounds and the month's label */
    private static function bounds(string $month): array
    {
        $start = \DateTimeImmutable::createFromFormat('Y-m-d H:i:s', $month . '-01 00:00:00', self::timezone());
        if ($start === false) {
            $start = new \DateTimeImmutable('first day of this month 00:00:00', self::timezone());
        }
        $end = $start->modify('first day of next month');
        $utc = new \DateTimeZone('UTC');
        return [$start->setTimezone($utc)->format('Y-m-d H:i:s'), $end->setTimezone($utc)->format('Y-m-d H:i:s'), self::label($start)];
    }

    private static function label(\DateTimeImmutable $month): string
    {
        return function_exists('wp_date') ? (string) wp_date('F Y', $month->getTimestamp(), self::timezone()) : $month->format('F Y');
    }

    private static function timezone(): \DateTimeZone
    {
        if (function_exists('wp_timezone')) {
            return wp_timezone();
        }
        return new \DateTimeZone('UTC');
    }

    private static function userName(int $userId): string
    {
        $user = function_exists('get_userdata') ? get_userdata($userId) : null;
        return is_object($user) && isset($user->display_name) ? (string) $user->display_name : '';
    }
}